Lost/dead companions

[Rokko]

Hello.
Just a simple question. How can I get back my companions whom I lost in battle ? Can they actually die ? I had 50 troops + 3 companions when I got defeated in a battle. So they took me prisoner and when I escaped it was only me and Podrick in my party. The other 2 companions I had was Dick crab ( or something like this ) and Sir someone... the knight from the crossroad in for the old valiria quest. Can anyone help me with this ?
Thank you

[boatswaiN]

Janis Lyren is dead RIP.

The others probably are prisoners at some castle

[Maester Rawl]

You can ask travelers in taverns the location of lost companions. If they're being held prisoner, you can attempt to break them out yourself or pay a ransome broker to get them released.